Enforcing max size for random samples

[masseyke]

This enforces the max size on the sampling config, and includes a new counter for documents rejected due to having exceeded the max size.
Note: I'm changing the serialization of SampleStats without including a new TransportVersion. This is safe because this object is not reachable in any released version, and is unavailable on serverless.

[Copilot]

Pull Request Overview

This PR implements maximum size enforcement for document sampling in Elasticsearch. It adds a new rejection counter for documents that exceed the configured size limit and prevents samples from growing beyond the specified maximum size.

• Added size-based filtering logic to prevent documents from being added when they would exceed the configured maximum size
• Introduced a new counter samplesRejectedForSize to track documents rejected due to size constraints
• Implemented efficient size calculation for sample collections with caching to optimize performance

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
SamplingService.java	Core implementation of size enforcement logic and new rejection counter
SamplingServiceTests.java	Added test coverage for maximum size enforcement behavior
SamplingServiceSampleStatsTests.java	Updated test infrastructure to handle new rejection counter
GetSampleStatsActionResponseTests.java	Updated test data generation for new stats field
GetSampleStatsActionNodeResponseTests.java	Updated test data generation for new stats field

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[Copilot]

Pull Request Overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

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[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[seanzatzdev]

Looks good to me overall, just left a few questions I'd like to discuss